Without scrapin' what dude? - The car on the road? I scrape sometimes now and I am at stock height still.
It depends on where you live...the lower you drop it, the less suspension travel you have, and also the larger your camber problems (unless you do it right and get a camber kit too
) - so it really depends on the roads, and how shitty you want the ride. I personally think that a 1.5" - 2" drop is about right - a good blend of looks without making the ride go-kart harsh.